Today I bought an early 80s Big Muff (MkIII). Or so I thought. When I got it home I found it sounded much different than other BMPs I've played/heard (including another MkIII Muff that I have) so I decided to open it up..... .....and found an original 4 transistor EH-3003 Big Muff Pi (MkI) board that'd been rehoused in a MkIII housing..... ....all for $20 more than what a new BMP RI would cost. SCORE!!!!! If anyone wants, I'll try to get pics of the circuit board up later.
Here's a bass through Big Muff clip..... http://www.ehx.com/ehx2/Catalog/04_..._Pi/24_Greta_Brinkman/02_G_Brinkman_BMuff.mp3 Honestly, it's not the best example of what it can do, but it is an example.